Brush-holder assembly for electric machine

ABSTRACT

This brush holder assembly for an electric machine comprises a bearing-forming metal end cap ( 26 ) intended to be mounted on a carcass of the machine, and a set of members ( 28, 30, 32, 34 ) for electrical connection of the brushes mounted on the end cap ( 26 ) by means of rivets ( 50, 52 ) which each include a shank extending from one of the pieces consisting of the end cap and one of the said members, passing through an orifice formed in the other piece and folded over against the latter. The shank is made of the same material as the piece from which it extends and includes a closed head. Application for the mounting of a brush holder for a motor-vehicle starter.

BACKGROUND OF THE INVENTION

The present invention relates to a brush holder assembly for an electricmachine, especially for a motor-vehicle starter, as well as a method ofassembling an electric machine provided with such an assembly, and anelectric machine featuring such an assembly.

STATE OF THE ART

According to one known configuration, a brush holder assemblyessentially includes a set of cages for electrical connection of thebrushes, a support plate made of electrically conducting material onwhich the cages are fixed, if appropriate with an electricallyinsulating board being interposed, as regards the cages intended to beconnected to a current-supply source, and a metal end cap forming abearing on which the support plate and the cages which it carries aremounted.

The assembly thus produced is mounted on the carcass of the electricmachine.

Conventionally, the support plate for the brush cages is mounted byscrewing onto the end cap, the screws used providing, on the one hand,the mechanical fixing of the support plate on the end cap and, on theother hand, its connection to earth.

This assembly technique exhibits a major drawback, given that theproduction of this type of brush-holder assembly is relatively difficultto automate in production lines and that the use of screws is likely togive rise to defects in assembly, due, for example, to faulty tighteningof the screws, or to damage to the threading of one of the screws.

According to one variant of this technique, described in WO 00/51209,for example, the support for the brush cages is fixed by means of rivetsonto the end cap. The use of rivets also makes the assembly difficult toautomate in production lines.

Another mounting technique consists in fixing the support plate bysandwiching it between the end cap and a yoke of the machine. The earthconnection for the support plate is thus made directly. However, thistechnique gives rise to problems of leaktightness to water, given thatthe junction areas between the support plate and the yoke, on the onehand, and the support plate and the end cap, on the other hand,constitute interfaces augmenting the risks of water penetration.

In addition to the above-mentioned drawbacks, these techniques requirethe use of specific interface pieces for fixing and connecting thecurrent-return brushes, which substantially reduces the electricalperformance of the brush holder assembly, gives rise to an increase inthe costs of manufacture and renders automation of manufacture morecomplex.

Another known technique consists in fixing the electrical-connectioncages of the brushes directly onto the bearing-forming end cap, ifappropriate with electrically insulating boards interposed. The fixingof the cages onto the end cap takes place, however, by means of rivetswhich render assembly of the unit difficult to automate.

OBJECT OF THE INVENTION

In the light of the foregoing, the aim of the invention is to remedy thedrawbacks of the state of the art and to provide a brush holder assemblyfor an electric machine, the assembling of which can be easily automatedin a production line, and at a reduced cost, and furthermore includingenhanced leaktightness to water.

Thus the object of the invention is a brush holder assembly for anelectric machine, comprising a bearing-forming metal end cap intended tobe mounted on a carcass of the machine, and a set of members forelectrical connection of the brushes mounted on the end cap by means ofrivets which each include at least one shank extending from one of thepieces consisting of the end cap and one of the said members, passingthrough an orifice formed in the other piece and folded over against thelatter, characterised essentially in that the said shank is made of thesame material as the piece from which it extends and includes a closedhead.

Hence, the cages for electrical connection of the brushes are mounteddirectly onto the end cap, which thus has a double function, whichreduces the number of pieces, simplifies and enhances the connection ofthe current-return brushes to earth. Moreover, the use of rivetsintegrated either into the cages or into the end cap greatly simplifiesthe fitting operation and renders the latter easy to automate. Finally,the use of a closed-head rivet makes it possible to obtain goodleaktightness to water.

This brush-holder assembly may also include one or more of the followingcharacteristics, taken in isolation or according to all the technicallypossible combinations:

the said shank is a hollow shank;

the shank consists of an extruded part of the piece from which itextends;

some of the members for accommodating and electrically connecting thesaid brushes consist of electrically conducting guide cages suitable foraccommodating a respective brush and fixed onto the end cap by means ofthe said rivets;

the or each rivet is made of the same material as the end cap;

the or each rivet is made of the same material as the guide cage;

some of the members for accommodating and electrically connecting thesaid brushes consist of electrically conducting guide cages suitable foraccommodating a respective brush and welded onto the end cap.

at least some of the members for guiding and electrically connecting thesaid brushes include electrically conducting guide cages suitable foraccommodating respective brushes, each guide cage being integral with aboard made of electrically insulating material fixed onto the end cap bymeans of the said rivets;

each guide cage is riveted onto the insulating board;

the or each rivet is made of the same material as the board;

the or each rivet is made of the same material as the end cap;

the guide cages are provided internally with elastic means pushing thebrushes radially, in operation, into abutment against a collector of theelectric machine, a member forming an end stop for limiting the radialdisplacement of the brushes in the absence of a collector furthermorebeing provided;

the member for limiting the radial displacement of the brushes includesa washer interposed between the brushes, on the outer wall of which thebrushes abut and the outer diameter of which is substantially greaterthan that of the collector;

the washer is connected to the metal end cap by frangible means suitablefor being broken by the collector in the course of its insertion betweenthe brushes.

the end cap is provided with a housing for accommodating the washerafter breaking of the frangible means.

the dimensions of the washer are suitable for obtaining a tight fit forthe latter on the end cap, at least when it is situated in the housing.

In one embodiment, the end cap features two raised areas for fixing andsupport of an electrically insulating board carrying the guide cages.

A clearance is thus formed between the two raised areas, which makes itpossible to form a ventilation space between the electrically insulatingboard and the end cap. Moreover, that makes it possible to fit the guidecages onto the board in advance.

In one embodiment, each raised area features a central area and twolateral areas, of lesser radial extent than the central area, extendingon either side of the central area.

By virtue of this arrangement, it is possible, by riveting onto theinsulating board, to fix the cages intended to be linked to a positivepower-supply terminal.

In fact, the difference in radial size of the lateral areas makes itpossible to install the rivets for fixing the above-mentioned cageswithout them being in contact with the end cap.

These rivets are then mounted in the region of the clearance between thetwo raised areas. These lateral areas delimit this clearance and, byvirtue of their shape, allow the installation of the rivets for fixingthese cages in the clearance between the two raised areas, extending, bydefinition, in projection with respect to the rest of the end cap. Theseraised areas are protuberances.

In order to optimise the clearance, the raised areas are generally increscent shape, with two lateral areas being connected to the outerperiphery of the central area.

The outer periphery of the lateral areas advantageously extends theouter periphery of the central area, in such a way that the outerperiphery of the raised areas, in one embodiment, constitutes a centringarea for the end cap with a view to fitting it in the manner of a cover,for example into the carcass or yoke of the rotating machine.

A further subject of the invention is a method of assembling an electricmachine provided with a brush holder assembly as defined above,characterised in that it includes the stages consisting in riveting themembers for electrical connection of the brushes onto the end cap,inserting the elastic means into the guide cages, positioning thebrushes in the guide cages, bearing against the elastic means, insertingthe member for limiting the radial displacement of the brushes, andpositioning the brush holder assembly thus produced around the collectorof the machine in such a way that the latter exerts a thrust on themember for limiting the displacement of the brushes such that the latterare freed from the said member.

Advantageously, the collector features, at its inner periphery, anaxially projecting collar of rounded shape, such as a godron, for actingon the inner periphery of the member for limiting the displacement ofthe brushes, so that the member does not become skewed.

In one embodiment, this member is a washer fitting tightly onto theinner periphery of a bush of axial orientation integral, for example bywelding, with the end cap.

This collar makes it possible to brake the armature shaft of theelectric machine.

Advantageously, an axial clearance exists, after fitting, between theend cap and the member for limiting the range of travel of the brushes.

In all cases, the end cap is a multi-function end cap and isadvantageously made of sheet metal so as to carry out these functions ina simple and economical way, given that the raised areas stiffen the endcap, which can thus be of slight thickness.

DESCRIPTION OF THE DRAWINGS

Other objects, characteristics and advantages will emerge from thefollowing description, given solely by way of non-limiting example, andgiven by reference to the attached drawings on which:

FIG. 1 is a view in perspective of a plate for supporting cages forelectrical connection of brushes of a brush holder assembly according tothe state of the art;

FIG. 2 is a view in perspective of an end cap of the brush holderassembly corresponding to the support plate represented in FIG. 1, onwhich the latter is to be fixed;

FIG. 3 is a view in perspective of a brush holder assembly in accordancewith the invention;

FIG. 4 is a view in section of a part of the end cap forming a bearingfor the assembly of FIG. 3, before assembly;

FIG. 5 shows the end cap of FIG. 4 after fitting of an insulating board;

FIG. 6 is a partial view in section along the line VI-VI of the brushholder assembly of FIG. 3;

FIG. 7 is a partial view in section along the line VII-VII of the brushholder assembly of FIG. 3;

FIG. 8 illustrates another embodiment of a brush holder assemblyaccording to the invention; and

FIG. 9 is a partial view in section along the line IX-IX of the brushholder assembly of FIG. 8.

FIG. 10 is a partial view in section of another embodiment example of abrush holder assembly in accordance with the invention, showing thecollector of the machine intended to be inserted between the brushes;

FIG. 11 illustrates the brush holder assembly of FIG. 10 in the courseof insertion of the collector between the brushes; and

FIG. 12 shows the brush holder assembly of FIGS. 10 and 11 aftercomplete insertion of the collector of the machine between the brushes;

FIG. 13 is a front view of the brush holder for a third embodimentexample;

FIG. 14 is a view in perspective of the end cap of FIG. 13;

FIG. 15 is a view in perspective of the wire lead-through;

FIG. 16 is a view in perspective of the insulating board;

FIG. 17 is a view in axial section along the lines 17-17 of FIG. 13;

FIG. 18 is a view in perspective of a hood for insulating a guide cage;

FIG. 19 is a view in perspective of a guide cage;

FIG. 20 is a partial view in section showing the position, afterfitting, of the member for limiting the displacement of the brushes;

FIG. 21 is a view similar to FIG. 13 for another embodiment example;

FIG. 22 is a partial view in axial section showing the central part ofthe end cap with its bush for another embodiment example.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

By reference to FIGS. 1 and 2, a brush holder assembly will first of allbe described according to the state of the art, for a motor-vehiclestarter.

This brush holder assembly essentially includes a metal support plate10, visible in FIG. 1, on which are fixed a set of electricallyconducting cages for connecting brushes 12, 14, 16 and 18, with a boardinterposed, such as 20, made of electrically insulating material, and anend cap 22 forming a rear bearing, visible in FIG. 2, on which are fixedthe support plate 10 and the cages 12, 14, 16 and 18 which it carries.The end cap 22, as can be seen in FIG. 2, includes, for example, twolugs 200, each traversed by a hole 201 for tie rods (not represented) topass through, screwed onto the front bearing of the starter asdescribed, for example, in the document FR-A-2 796 990. The frontbearing of the starter carries the pinion of the inertia gear starter ina way which is known in itself, as, for example, in the documentsFR-A-2,783,090 and FR-A-2 796 990.

Two of the cages, namely the cages designated by the numericalreferences 12 and 14, intended to accommodate current-return brushes,are connected to the support plate 10 by means of appropriate conductors124.

The support plate 10 is fixed by being screwed onto the bearing-formingend cap 22.

The screws used for fixing the support plate 10 onto the end cap 22provide, on the one hand, the mechanical fixing of the plate 10 on thelatter and, on the other hand, its electrical connection to earth.

However, and as set out above, the use of such screws makes theassembling of the brush holder assembly difficult to automate inautomated production lines, and is likely to give rise to defects inassembly.

By reference to FIGS. 3 to 7, a first embodiment example of a brushholder assembly according to the invention, making it possible toovercome these drawbacks, will now be described.

This brush holder assembly, designated by the general numericalreference 24, is intended to be mounted on a carcass of an electricmachine consisting of a motor-vehicle starter.

Referring first of all to FIG. 3, the brush holder assembly 24essentially includes a metal end cap 26 forming the rear bearing of theelectric machine, and a set of members 28, 30, 32 and 34 forelectrically connecting the brushes, which are fixed onto the end cap 26by means of rivets.

In a way which is known in itself, for example from the document FR-A-2796 990, the bearing-forming end cap 26 is provided with a centralnon-through cell 35 in which the armature shaft of the electric machineis intended to be journalled.

This cell is delimited by a bush 35′ of axial orientation, describedbelow.

In the embodiment example which can be seen in this figure, the membersfor electrically connecting the brushes include a set of electricallyconducting guide cages 36, 38, 40 and 42 each intended to accommodateand guide a brush, such as 44, and an electrically insulating board 46,produced from a material appropriate to the use envisaged, for example amouldable material, such as a plastic.

The guide cages are of metal here, being here of sheet metal pre-platedwith copper such that the solution is simple and economical.

As is conventional, the brushes 44 are intended to come into contactwith collecting tracks of an axial commutator or collector which theelectric machine features, an elastically deformable member, placed inthe cages 36, 38, 40 and 42, pushing the brushes radially into abutmentagainst the collecting tracks.

The collecting tracks are of axial orientation and the brushes 44 ofradial orientation in order to reduce the axial bulk of the electricmachine.

Some of the cages, namely the two cages designated by the numericalreferences 36 and 38, are intended to accommodate negative orcurrent-return brushes, the other cages, namely the cages designated bythe numerical references 40 and 42, being intended to accommodate thecurrent-supply brushes.

These brushes are linked electrically, in the case of a starter, to oneof the power-supply terminals of the electromagnetic contactor of thestarter.

Hence, electrically conducting cables, such as copper braiding 48,enable, on the one hand, the power supply for two of the current-supplybrushes by way of a grommet 49 intended to pass through the carcass ofthe electric machine so as to provide the connection between thesebrushes and a positive power-supply terminal and, on the other hand, theearth connection of the current-return brushes 44 by connection of thecorresponding cables, for example by welding, to the end cap 26.

As will be described in detail in what follows, a washer 64, forming adummy collector, allows the fitting of the brush holder assembly whilepushing back the brushes towards the outer periphery.

At least two orifices 301, formed through the metal end cap 26, allowtie rods to pass for fixing of the end cap. In this case, the tie rodspass between the magnets which are fixed within the carcass in order toform the inductor. These tie roads are screwed into tappings formed, forexample, in the front bearing of the starter carrying the front end ofthe armature shaft, the rear end of which is visible in FIGS. 10 to 12and 20.

The tie rods here pass inside the carcass, conventionally of cylindricalshape and made of metal, which the machine features as can be seen, forexample, in the document FR-A-2 796 990. It is via this carcass that theearth return is provided.

Referring also to FIGS. 4 to 7, the guide cages 36, 38, 40 and 42 arefixed onto the insulating board 46 by means of rivets, such as 50.

The insulating board 46, for its part, is fixed onto the bearing-formingend cap 26 by means of rivets 52.

As represented in FIGS. 4 to 6, according to one characteristic of theinvention, the rivets 52 used for fixing the board 46 onto the end cap26 each take the form of a hollow shank 54 made from the same materialas the end cap 26 in order not to impair the leaktightness thereof.

The hollow shank 54 is produced by extrusion in the course of themanufacture of the end cap 26, by striking the latter against theimprint of a female mould so as, during the removal from the mould, toform a shank 54 in the form of a collar made from the same material asthe end cap 26 and extending in projection from one of its large faces.

As can be seen in these figures, the shank 54 of the rivet 52 includes abottom 56 closed off by the material of the end cap 26.

For integrating the insulating board 46 and the end cap 26, the shank 54of each rivet 52 passes through an orifice formed in the insulatingplate 46 and is turned down, at its free end, against the latter.

In the embodiment example described by reference to FIGS. 4 to 6, therivets are made of the same material as the bearing-forming end cap 26.

Needless to say, it is possible to produce these rivets from theinsulating board 46, by extrusion, in such a way as to form, in thelatter, a hollow shank with a closed bottom being engaged in an orificeformed in the end cap 26.

The riveting is then carried out hot.

Referring now to FIG. 7, the metal guide cages are, for their part,fixed onto the insulating board 46 by means of conventional, appliedrivets 50 or by means of rivets similar to the rivets described above,that is to say either respectively made from the same material as thecages, or made from the same material as the insulating board 46.

As can be imagined, the brush holder assembly which has just beendescribed, which uses brush-guidance cages, here made of metal, fixeddirectly onto the bearing-forming end cap of the electric machine whichthey are intended to power, using rivets made of the same materialeither as an insulating board on which the cages are fixed, or as theend cap, allows assembly of the unit by means of automatic machines,while reducing costs and substantially enhancing the thermal exchangesbetween the cages and the end cap.

Moreover, very good leaktightness to water is obtained, given thatrivets are used consisting of shanks with a closed bottom.

Needless to say, in a variant, the cages are made of plastic.

It will be noted, however, that the invention is not limited to theembodiment described.

In fact, in the embodiment example described above by reference to FIGS.3 to 7, the two current-return brushes are connected to earth by way ofconductors connected to the end cap 26.

As can be seen in FIGS. 8 and 9, in which elements identical to those ofFIGS. 3 to 7 are designated by the same numerical references, it ispossible to fix the cages 36 and 38 directly onto the end cap 26 bymeans of rivets similar to those described above, that is to say takingthe form, for example, of hollow shanks made of the same material eitheras the cages 36 and 38 or as the end cap 26, so as to provide for theirmechanical fixing on the end cap 26 and their electrical connection withthe latter, the other cages 40 and 42, for their part, being fixed asdescribed above onto the insulating board 46 by riveting. The board 46is then simplified.

Needless to say, these current-return cages can also be welded directlyonto the end cap 26.

It will be noted, finally, that it is possible to produce each rivetaccording to any appropriate form for the use envisaged, that is to sayin the form of a solid shank, of shanks in the form of claws.

By reference to FIGS. 10 to 12, another embodiment example of a brushholder assembly in accordance with the invention will now be described.

In these figures, elements identical to those of the brush holderassemblies described above by reference to FIGS. 3 to 9 bear the samenumerical references. The same is true in FIGS. 13 to 20.

Referring first of all to FIG. 10, as in the embodiment exampledescribed above, the brush holder assembly includes a metal end cap 26forming the rear bearing of the electric machine, and a set of cages,such as 38 and 40, each intended to accommodate and guide a brush, suchas 44, which is intended to come into contact with collecting tracks ofa collector 60 of the electric machine.

Some of the cages, here made of metal, are intended to accommodatenegative or current-return brushes, the other cages being intended toaccommodate the current-supply brushes.

The brush-guidance cages are fixed onto the end-cap 26 by means ofrivets identical to those described previously with an insulating board46 interposed, at least as regards the power-supply brushes.

As regards the bearing-forming end cap 26, it is provided with a centralcell 35 of generally cylindrical shape, blind, in which the armatureshaft 62 of the electric machine is intended to be journalled.

The cell 35 is delimited by a bush 35′ described below.

As indicated above, the brushes 44 are inserted into the cages 38 and 40with an elastic member represented at 45 in FIG. 17 inserted, pushingthe brushes, in operation, into abutment against the collecting tracksof the collector 60 of the rotating electric machine.

In the non-assembled state, visible in FIGS. 10, 11 and 17, and, inparticular, when the collector 60 has not yet been inserted between thebrushes 44, a member for limiting the radial displacement of the brushesis used, against which these brushes come to abut in the absence of thecollector 60.

More particularly, and as mentioned above, this limiting member,designated by the overall numerical reference 64, takes the form of awasher, described below, inserted between the brushes 44 and against theperipheral wall of which the brushes 44 come to abut.

The outer diameter of the washer 64 is substantially larger than thecorresponding diameter of the collector 60, so as to delimit a spacesufficient to allow the latter to be inserted.

As can be seen in FIG. 10, the washer 64 is inserted on the outerperiphery of the cell 35 of the end cap 26, that is to say on the bush35′.

Referring now to FIGS. 11 and 12, upon insertion of the collector 60,the collector exerts a force on the washer 64 such that it displaces thelatter along the brushes. At the end of travel of the collector 60, thatis to say when the latter is fully inserted between the brushes 44, thewasher 64 comes to be lodged in a clearance 66 formed for this purposein the end cap 26. In this position, the brushes are released from thewasher 64 and then come into abutment, under the action of the elasticmeans provided for this purpose, against the collecting tracks of thecollector 60 integral with the armature shaft 62 of the machine.

For preference, as in FIG. 3, the inner diameter of the washer 64 ischosen so as to obtain a tight fit between the latter and the outerperiphery of the bush 35′ of the cell 35, in the holding position, so asto prevent it bouncing around in the housing 66, which would be likelyto give rise to noise during the operation of the starter. Needless tosay, before assembly, this washer is held by the radially inwardspressure exerted by the brushes pushed by the springs 45.

As can be imagined, after assembly of the electric machine, the washer64 constitutes a surface against which the free end of the collectorcomes to bear, as can be seen better in FIG. 20. This surface can beused to brake the armature rapidly when stopping the electric machine.The noise generated in the course of the slowing-down period is thusconsiderably reduced. This characteristic is particularly advantageouswhen the electric machine consists of a motor-vehicle starter, giventhat it makes it possible to reduce the dead time between two startingattempts.

It can easily be imagined that the washer 64 can be used to carry outaxial setting-up of the armature.

For these applications, an elastic member is preferably provided betweenthe washer 64 and the end cap 26 so as to push it into abutment againstthe collector.

In the embodiment example which has just been described, the washer 64is regarded as consisting of a member separate from the end cap 26 onwhich it happens to be mounted.

Needless to say, in particular in the case in which the endcap 26 isproduced by moulding from a plastic, the washer 64 can be produced inthe form of a member moulded from the same material as the end cap 26and connected to the latter by frangible means, for example in the formof arms suitable for being broken by the collector 60 in the course ofits insertion.

It will be noted that the operation of assembling an electric machineprovided with a brush holder assembly according to this embodimentexample is an operation which is relatively easy to carry out in ahigh-throughput production line, given that, after riveting of themembers for electrical connection of the brushes onto the end cap 26, itis convenient to simply insert elastic means into the guide cages, toposition the brushes 44 in the cages, in abutment against the elasticmeans, to insert the washer 64 on the bush 35′ of the cell 35 in such away as to space the brushes apart sufficiently to allow the collector 60to be inserted, then finally to insert the collector in such a way thatthe armature shaft 62 is inserted into the cell 35.

A bearing, referenced 500 in FIG. 20, is interposed radially between theend of the armature shaft and the inner periphery of the bush 35′ forthe journalling mounting of the shaft 62 such that the end capconstitutes the rear bearing of the electric machine.

As indicated above, in the course of the insertion of the collector 60,the latter exerts a thrust on the washer 64 until it comes to be engagedin the clearance 66 and releases the brushes which from then on comeinto abutment against the collecting tracks of the collector.

Next comes the actual fixing of the end cap 26 onto the rest of themachine, by the use of tie rods, in a manner known in itself.

Finally it will be noted that the arrangement described above byreference to FIGS. 10 to 12, in which a washer is used for holding thebrushes which come to be positioned in the housing, after the starterhas been assembled, constitutes a construction independent of the typeof assembly used for the fixing of the members for electricallyconnecting the brushes.

As is revealed clearly in the description and drawings, the end cap 26,forming a rear bearing, features raised areas for fixing and supportingthe board 46 made of electrically insulating material.

These raised areas stiffen the end cap 26, carry the rivets 52 forfixing the board 46, and define flat areas for the board 46 to rest onand be supported.

The end cap 26, in one embodiment, is obtained by moulding, especiallywhen it is based on aluminium.

Advantageously the end cap 26 is made of stamped sheet metal, such thatproduction is simple and economical.

Moreover, this makes it possible to lighten the end cap 26 and to reducethe thickness thereof, which is favourable to the reduction in the axialbulk of the electric machine, for example a motor-vehicle starter.

This is because the raised areas are obtained by stamping, such that theend cap 26 features hollow areas on its outer face. These raised areasstiffen the end cap 26, which can thus have a reduced thicknessfavourable for being stamped.

In all the figures represented, the end cap 26 is a closure piecewithout holes such that it is leaktight.

It will also be appreciated that the raised areas allow the creation,between them, of a clearance referenced 129 in FIG. 7. This clearancemakes it possible to create a space between the board 46 and the end cap26.

By virtue of this space the rivets 50 for fixing the metal cages 40, 42will not come into contact with the end cap, such that any short-circuitis avoided.

By virtue of the clearance 129, a ventilation space exists between theboard 46 and the end cap 26.

Needless to say, the present invention is not limited to the embodimentexamples described.

In particular, it is possible to shape the end cap 26, in annular form,so that the latter comes into intimate contact with the cylindricalcarcass of the electric machine represented partly in dashed lines as100 [sic] in FIG. 12.

It is within this carcass, in a known way, that the armature of theelectric motor of the electric machine is housed, the shaft of whichbears the reference 62. The carcass is produced, for example, by rollingof a metal plate and stapling thereof. The end cap 26 constitutes acover for closing of the carcass 100.

Needless to say, it is possible to optimise the shape of the raisedareas.

Thus, as can be seen in FIGS. 13, 14, the end cap 26 features two raisedareas 126, 127 face-to-face and extending symmetrically on either sideof the diameter D-D of FIG. 13.

Each raised area is obtained here by stamping of the sheet-metal end cap26, and features a central fixing area 130 and two lateral stabilisationareas 131, 132 extending circumferentially on either side of the centralarea 130. The raised areas are obtained on a press by the technique ofsemi-cutout.

The raised areas 126, 127, in this embodiment, are in crescent shapeoverall, with two lateral areas 131, 132 being connected to the outerperiphery of the central area 130.

The outer peripheries of the areas 131, 132 extend the outer peripheryof the central area 130.

The upper face of the raised areas 126, 127 is flat for the board 46,made of electrically insulating material, here Bakelite, to rest on andbe supported.

Each central area 130 features the rivets 52 for fixing the board 46made of the same material as the end cap 26; each rivet 52 featuring ashank 54 made of the same material as the end cap 26 in theabove-mentioned way.

Each central area 130 is of greater radial extent than the two lateralareas 131, 132 called stabilisation areas, since they serve solely forthe board 46 to rest on, while the central area 130 serves for thesupport and the fixing of the board 46.

The lateral areas 131, 136 are in the form of an annular sector.

The central area 130 has a trapezoidal shape overall; its innerperiphery 133 being circular so as to let through the washer 64 forholding the brushes 44.

The diameter over which the inner peripheries of the raised areas 126,127 are installed is therefore greater than the outer diameter of thewasher 64.

Likewise, the board 46 features a central bore letting through thewasher 64. The inner diameter of the board 46 is therefore greater thanthat of the washer 64.

This washer 64, at its outer periphery, features a washer extendedradially inwards by a central part subdivided into tabs 164 by virtue ofblind slots 165 separating the tabs 164 in pairs. The slots 165 areradial slots, which open out into the central aperture of the washer 64.

The washer 64 here features an elasticity which allows it to be clamped,in the above-mentioned way, onto the bush 35′ of the cell 35.

Here, as in FIGS. 10 to 12, the end cap 26 is stamped centrally so as toform a protuberance 235 (FIGS. 17, 20) extending in a direction oppositeto the raised areas 126, 127.

This protuberance includes a concave frustoconical bearing surface 335on which is fixed, by welding, the chamfered end of the bush 35′, heremade of metal. The welding can be carried out by any type of welding,such as arc welding, resistance welding and laser welding.

The end cap 26 thus exhibits a supplementary function, namely a functionof support for the bush 35′ delimiting the cell 35. The cell 35 belongsto the central part of the leaktight end cap 26. The concave bearingsurface 335 belongs to a frustoconical wall, which is connected to theinner periphery of the peripheral part of the end cap including theraised areas.

This bush 35′ itself has a double function, namely a function of supportfor the washer 64 at its outer periphery and, at its inner periphery, afunction of support for a bearing 500, here a smooth bearing but in avariant a needle bearing, for the end of the armature shaft 62 of theelectric motor of the electric machine.

The end cap 26 thus equipped constitutes the rear bearing of theelectric machine.

The electrically insulating board 46 is of simple and economic form, andfeatures a flat edge 146 and two recesses 147 as well as a central borefor the washer 64 to pass through.

As can be seen in FIG. 13, the recesses 147 are provided in order not toblock the holes 301 and to let through the tie rods (not visible) forfixing of the end cap 26, constituting the rear bearing. The flat edge146 makes it possible to free the central area 130 of the raised area127 for welding of the ends of the conductors 48 of the brushes of thecurrent-return cages 36, 38 to the central area 130 of the raised area127 as can be seen in FIG. 13, the welds being represented in black.

The clearances 147 are diametrally opposite. The depth of the clearances147 is a function of the diameter of the holes 301. The clearances hereare U-shaped. The position of the holes 301 on either side of thediameter D-D is due to the installation of the tie rods in the region ofthe front bearing of the electric machine.

The board 46 also features holes for the passage of the hollow-shank 54rivets 52 and rivets 50, here in a single piece with the cages 36, 38,40, 42.

As can be seen in FIG. 13, the current-return cages 38, 36, hereinstalled at 120° with respect to one another, and the current-supplycages 40, 42, also installed here at 120° with respect to one another,are arranged on either side of the diameter of symmetry D-D constitutingthe axis of symmetry of the recesses 147. The cages 42 and 38 areinstalled symmetrically on either side of the diameter D-D with anangular offset of 60° with respect to one another. The same is true forthe cages 40 and 46.

Thus the cages 42 and 36 are diametrally opposite and the same is truefor the cages 40 and 38. The axes of the cages are therefore arranged inan X-shape in order to leave a large circumferential distance betweenthe two cages respectively for current supply and for current return, soas to have a large offset between the rivets 52 of the same raised area.Needless to say, depending on applications, it is possible to alter theangles between the cages while having an X-shaped arrangement of theaxes of the cages arranged, on the one hand, symmetrically with respectto a diameter of the end cap 26, overall in disk shape, and, on theother hand, circumferentially in an irregular way.

These metal cages, as can be seen better in FIG. 19, have a U-shapeoverall with a bottom serving for the guidance of the associated slider44.

The U-shaped branches are each equipped centrally with a cylindricalarea for defining a cylindrical housing for the mounting of the returnspring 45, here of the coil-spring type, pushing the brush 44 towardsthe centre. Each brush 44, as can be seen better in FIG. 17, features astud (not referenced) for centring of the lower end of the spring 45,the upper end of which bears on retaining claws 381 arising from thebranches of the cages.

More precisely, the spring 45 and the brush 44 are mounted in each cage,then the claws 381 are closed over so as to lock the spring 45; thewasher 64 being, needless to say, in position so as not to lose thebrushes 44.

Needless to say, one of the branches of the cage features a blind slot(not referenced in FIG. 19) for the conductor 48 integral with eachbrush 44 to pass through.

Here, two claws 381 for retaining the spring 45 in question are providedper branch.

The claws 381 are turned towards one another and are produced bycutting-out by way of a slot. The free ends of the branches of the cagesare each extended by a wing (not referenced in FIG. 19) extendingparallel to the bottom of the cage. The wings are intended to come intocontact with the board 46 and are shaped so as to feature the rivets 50here made of the same material as its wings. The wings are thereforewings for fixing the cages and are obtained by folding, because thecages are made of metal.

The metallic nature of the cages makes it possible to simplify themwhile giving them the shape and the functions desired. The cagestherefore have a simple and economical form.

In order to avoid any short-circuit, the current-supply cages 40, 42are, in a variant, closed off by a hood 140 made of electricallyinsulating material, here of mouldable plastic.

Each hood 140 covers over the branches of the cages 40, 42 in the regionof the claws 381 thereof. Each hood 140 includes a bottom bearing twohalf-pins 141, 142 each equipped with ribs 143 intended to be forciblyengaged between the two branches of the cages on either side of thecylindrical portions thereof, that is to say on either side of the claws381.

Each hood includes a peripheral rim perpendicular to its bottom. Thisrim is interrupted in the region of the half-pin 141 intended to comeinto engagement locally by its ribs with the part of the branches of thecages which is adjacent to the wings bearing the rivets. The cages 40,42 are thus each looped by the rim of the hood 140 thus being mounted byclipping into the cages featuring an elasticity for radially closing offthe upper part thereof.

It will be appreciated that the insulating board 46 offers an abutmentto the brushes and supports the cages.

The other raised area 126 is extended outwards by a claw 134 extendingradially in projection with respect to the outer periphery 135 of theend cap 26, overall in the form of an annular disk. It is on this claw134 that the grommet 49 is mounted, in bracket shape overall. To dothis, the grommet 49 (FIG. 15) features an upper wing 153 extended by aportion (not referenced) featuring a hole 152 intended to be engaged ina complementary way onto the claw 134 of rectangular section like thehole 152.

By virtue of the hole 152 the grommet 49 is fixed onto the hood 26,given that its other wing 150, perpendicular to the upper wing 153, isintended to come into contact with the upper face of the board 46.

This wing 150, according to one characteristic, is elongatedcircumferentially so as to cover over the two fixing rivets 52 made ofthe same material as the end cap 26. Thus, any short-circuit between therivets 52 and the conductors 48 of the cages 40, 42 is avoided. Thesetwo conductors 48 are fixed, for example by welding, onto anelectrically conducting linking element 148 passing through a passagehole 149 provided in the upper wing 153 with rounded free end. The edgeof the wing 153 is provided with a groove 151 for mounting the grommetonto the edge of a recess formed at the end of the metal carcass or yoke100. The height of the groove 151 is a function of the thickness of thecarcass 100. The recess in the carcass 100 has a shape complementary tothat of the bottom of the groove 151.

Thus, the wing 153 closes and seals the recess of the carcass, thusfeaturing a rounded bottom, because the flanks of its groove cover overthe carcass.

The grommet 49 is therefore mounted by axial threading onto the carcass100, advantageously with a tight fit. The grommet 49, made of flexibleand deformable electrically insulating material, such as elastomer orrubber, in addition to the electrical-insulation functions, carries outfixing functions; the groove 151 being mounted tightly on the carcass100, the hole 152 being mounted tightly on the free end of the claw 134,while the linking piece 148 passes tightly through the hole 149.

Because of these tight fits, good leaktightness is obtained.

The grommet 49 is therefore also a sealing piece.

It will be appreciated that the outer periphery 128, of annular shape,of the raised areas 126, 127 extends slightly radially below the outerperiphery 135 of the end cap 26. The diameter of the outer periphery 135of the end cap is therefore slightly greater than that of the outerperiphery of the raised areas 126, 127.

This difference in diameter is a function of the thickness of thecarcass 100, such that the carcass comes into abutment on the end cap 26beyond the outer periphery 128 as can be seen in FIG. 17.

The outer periphery 128 of the raised areas is in intimate contact withthe inner periphery of the carcass as can be seen in this FIG. 17.

The outer raised-area periphery 128, of cylindrical shape overall,having regard to the height of the raised areas 126, 127, thus defines acentring diameter on the yoke 100.

The end cap is therefore mounted centred on the yoke 100 by nesting intoit. Needless to say, the edges of the raised areas are radiused, as canbe seen in FIG. 14, by virtue of the fact that they are obtained bystamping.

In this FIG. 14, the bush 35′ has not yet been fixed onto the end cap26.

In FIGS. 13 to 20 the thickness of the raised areas is greater than thethickness of the washer 64 such that the presence of the clearance 66 ofFIGS. 10 to 12 is not necessary, the clearance 129 between the raisedareas carrying out this function. Needless to say, it is possible toprovide an abutment washer for the end of the armature shaft 62, as canbe seen at 400 in FIG. 17. In this case the washer 400 is mounted in thebottom of the protuberance 235.

Assembly is carried out as in FIGS. 10 to 12, FIG. 17 representing thebrush-holder assembly before fitting of the collector, and FIG. 20representing the position just after complete insertion of the collectorbetween the brushes.

This collector 60 features electrically conducting tracks 161 carried bya support 160 made of electrically insulating material.

The support 160 is conventionally made of plastic, its inner bore beingstaged in diameter, as can be seen in FIG. 20, for housing the bush 35′;the free end of the armature shaft 62 being of reduced diameter for itsrotational mounting in the bearing 500 carried internally by the bush35′. The support 160 is integral with the armature shaft 62, in a knownway.

According to one characteristic, the support 160 features, at its freeend, a collar 163 of axial orientation, here made of the same materialas the support 160, by moulding.

The collar 163 is installed at the inner periphery of the support 160and therefore of the collector 60.

The collar 163 extends the internal bore of the support 160, and, in avariant, is subdivided into annular sectors by slots promotingventilation.

Here the collar 163, of annular shape, is of short axial length, suchthat it has the shape of the annular-shaped bead.

The free end of the collar is of rounded shape for local contact withthe washer 64.

Here the collar has a godron shape. During assembly the collector 60therefore pushes on the washer 64 for retaining the brushes 44 on theinner periphery thereof, such that the latter does not risk beingskewed.

The godron 163 therefore comes into contact with the tabs 164 of thewasher so as axially to displace the washer 64 mounted tightly on thebush 35′.

There is therefore no fear of skewing.

Finally, after mounting on the carcass 100, a clearance J exists betweenthe washer 64 and the end cap 26, and the godron 163 is in contact withthe washer 64. This clearance avoids direct transmission of heat betweenthe end cap 26 and the washer 64, while forming a ventilation spacebetween them. Moreover, this makes it possible to get roundmanufacturing tolerances and to ensure release of the brushes 44, afterassembly of the machine.

When the electric motor of the machine stops, there is therefore brakingof the armature shaft by virtue of the godron in contact with the washer64.

A device for braking the shaft is produced. Advantage is taken of thetight fitting of the washer 64.

The godron 163 has a double function, and thus constitutes both a toolfor axial displacement of the washer 64 for freeing the brushes 44, anda member for braking the shaft 62 integral with it.

Needless to say, it is possible to invert the structures. For example,the protuberance 235 can be turned towards the collector 60 and thefrustoconical bearing surface of the bush 35′ can be formed at the innerperiphery thereof. In this case, it is necessary to provide a clearancefor accommodating the washer as can be seen at 66 in FIGS. 10 to 12.

The collar 163 may be longer axially.

The height of the raised areas 126, 127 depends on the applications,these delimiting a clearance for at least partially accommodating thewasher 64 after assembly of the machine.

The central area 130 can be extended so as to dispense with the lateralareas associated with the cages 36, 38 linked to earth, when these cagesare fixed directly onto the end cap as can be seen in FIG. 9.

One of the raised areas can therefore be devoid of lateral wings.

Here, the cages 40, 42 are advantageously side by side. Needless to say,in a variant, they can be diametrally opposite. In this case it isnecessary to provide two grommets.

In connection with the fixing method of FIG. 9, it is seen that eachraised area may include only one lateral area of lesser height than theother fixing area.

It will be appreciated that the washer 64 for limiting the radialdisplacement of the brushes is of universal usefulness and thereforeapplies equally to the solutions described in pages 1 and 2 of thedescription.

The same goes for the collar 163 and the raised areas 126, 127 creatinga clearance for the members for fixing the cages to the board 46.

Needless to say, the electric machine may be an actuator for control ofthe wiper blades of a motor vehicle, or for control of the ventilatorfor cooling the vehicle. In a variant, the washer is integral at itsinner periphery with a sleeve mounted tightly on the outer periphery ofthe bush 35′ such that the member for limiting the brushes beforeassembly of the machine may take different forms.

In the case or [sic] this member includes a sleeve, the tight fit isobtained, in one embodiment, with the aid of seals mounted in grooves ofthe sleeve and fitting tightly on the bush 35′. In a variant, thesleeve, advantageously made of plastic, is equipped at its axial endswith tabs fitting tightly on the bush 35′, which belongs to the end cap26.

In a variant, the outer periphery of the bush 35′ has notches or aknurling for forcible fitting of the washer 64, then advantageouslydevoid of tabs and less hard than the bush.

In all cases, the tight fit is determined so as to allow an axialdisplacement of the limiting member 64, advantageously comprising awasher.

In a variant, the raised area 127 centrally carries a single rivet 52(FIG. 21), and two bosses 227 of oblong shape arranged symmetricallywith respect to the above-mentioned rivet 52. The board 46 then, in theregion of the raised area 127, features, at its inner periphery, aV-shaped contour so as to create a clearance for the bosses 227 servingfor precise welding of the bared ends, shown diagrammatically bycrosses, of the conductors 48.

In FIG. 20, the bush 35′ is chamfered externally so as to co-operate incentring with the bearing surface 335. In a variant (FIG. 22) thisfrustoconical bearing surface 445 is convex, such that the bush 35′ ischamfered internally so as to co-operate in centring with this bearingsurface 445 in order to be welded in a more resistant way onto it. Thisarrangement leads to increasing the length of the yoke. In order toalleviate this drawback, the bearing surface 445 is connected to theinner periphery 300 of the peripheral part of the end cap 26 by way of aconcave frustoconical bearing surface 555. The bearing surfaces 445, 555belong to frustoconical walls inclined in the reverse direction and,seen from the outside, delimiting an annular bead with a rounded peakand with inclined flanks and, seen from the inside, an annular groovewith inclined flanks and with a rounded bottom. The bottom 655 of theprotuberance, delimited by the bearing surface 445, is here in the planeof the inner periphery 300 of the peripheral part of the leaktight endcap 26. In a variant, the bottom 655 extends in projection or in reliefwith respect to this inner periphery. By virtue of this arrangement, thewelding of the bush is resistant while increasing the axial length ofthe carcass less than with a solution with a uniquely convex bearingsurface. The solution of FIG. 22 leads to a double stamping operation.

1. Brush holder assembly for an electric machine, comprising abearing-forming metal end cap (26) intended to be mounted on a carcassof the machine, and a set of members (28, 30, 32, 34) for electricalconnection of the brushes mounted on the end cap (26) by means of rivets(50, 52) which each include at least one shank (54) extending from oneof the pieces consisting of the end cap (26) and one of the said members(28, 30, 32, 34), passing through an orifice formed in the other pieceand folded over against the latter, characterised in that the said shank(54) is made of the same material as the piece from which it extends andincludes a closed head (56).
 2. Brush holder assembly according to claim1, characterised in that the said shank (54) is a hollow shank.
 3. Brushholder assembly according to claim 1, characterised in that the shank(54) consists of an extruded part of the piece from which it extends. 4.Brush holder assembly according to claim 1, characterised in that atleast some of the members for guiding and electrically connecting thesaid brushes include electrically conducting guide cages (40, 42)suitable for accommodating respective brushes (44), each guide cagebeing integral with a board (46) made of electrically insulatingmaterial fixed onto the end cap (26) by means of the said rivets (52).5. Brush holder assembly according to claim 4, characterised in thateach guide cage (40, 42) is riveted onto the insulating board (46). 6.Brush holder assembly according to claim 4, characterised in that theend cap (26) features raised areas (126, 127) for mounting the board(46).
 7. Brush holder assembly according to claim 6, characterised inthat the raised areas (126, 127) feature at least one area (130) forfixing the board (46) and a lateral area (131, 132) of lesser radialextent for creating a clearance (129) allowing at least one guide cageto be fixed.
 8. Brush holder assembly according to claim 13,characterised in that the raised areas feature two lateral areas (131,132) extending on either side of a central area (130) for fixing theboard, and in that the lateral areas are connected to the outerperiphery of the central area (130) having a lesser radial extent thanthe central area (130).
 9. Brush holder assembly according to claim 8,characterised in that one of the raised areas (126, 127) is extended bya claw (134) for mounting a grommet (49).
 10. Brush holder assemblyaccording to claim 4, characterised in that the guide cages are providedinternally with elastic means pushing the brushes radially, inoperation, into abutment against a collector of the electric machine, inthat it includes a member (64) forming an end stop for limiting theradial displacement of the brushes in the absence of a collector and inthat the end cap (26) centrally carries a bush (35′) on the outerperiphery of which the member (64) is tightly fitted.